Can't locate replacement shower diverter

Recently had a running tub in guest shower of my older home (`60's). I purchased a 3 handle rebuild kit that came with 3 valves, new seats, trim plates, sleeve covers and new knobs. Everything went in great except the diverter valve from the kit doesn't thread in and nothing at 2 local stores looks compatible (tried ace hardware & home depot). Additionally the old valve leaks a bit as water comes out of the tub spout when using the shower, and when I was taking it apart the knob was seized onto the splined end so I had to break the splined end off to remove the knob, so now I'm really stuck!

I found a link on here to a shop in NY arpny.com that has an online catalog of valves. I believe I have ID'd the valve as an Arrowhead Brass ARR5003 but I can't seem to find anywhere online to purchase this, and the arrowhead brass website I found doesn't even list diverter valves.

Can anyone help?

Here's a picture of the old valve vs the one from the catalog for comparison - note the splined end I had to break off to remove the old knob.

To me, it looks EXACTLY like a Price Pfister diverter stem. However, it comes in two versions. One with the thread where yours is, "Beaux art style, and the other with the threads just under the "flange", "contempera/verve" style. If it is, call 1-800-PFAUCET and get an address where you can send the picuture and they will be able to send the correct one.

It looks like Price Pfister to me also, but "Beaux Art" not "Verve". "Verve" would not have the chrome plating and the threads on the bottom of the gland would be located differently. The "Beaux Art" is just over 5" tall while the "Verve" is a little over 5 1/2". The stem in your second picture looks correct to me.